PIEZO NXT type panel

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#301
And how it looks like.
 

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#303
I'm not in to technical response curves as such, but I can see that 2 piezos in phase increase output at their most efficient frequencies?In my experience, as more exciters were used, the sound got better and better - it's as simple as that.
To this day, I find no abnormal resonances (but the panels are still not properly mounted and supported - that may be another story?).

Also, according to your set up, you must NEVER place an exciter in the exact middle of a panel, be it round, square or rectangular. I read this on some NXT application notes somewhere a while back.This may be the reason for some of the resonant peaks?

I have never taken most people's suggestions seriously on using push pull exciters. Your response and experiment proves this - well done!🙂
 
#305
There is no decent price for this material. I have checked and it is pure robbery - extremely overpriced for what it is(especially in large sizes, plus enormous shipping charges unless you live next door to the factory that makes it).

That's why I use Gatorfoam. NXT have used it in some of their products and have advised me directly of this fact. So, for the little gain that will be obtained from using the honeycomb panel - it's NOT worth it:xeye:
 
#307
jzagaja, the pistonic exciters are FAR SUPERIOR to any Piezo. I know, I've been there and done that as you will find at the beginning of this thread and what followed on from there.

As an example, I tried a piezo on my panels as an addition to the pistonic NXT exciters. The result sound wise?............the piezo could not penetrate the highs through the panels where the NXT exciters could (much better).Secondly, with Piezo's you will never obtain any bass or low notes - it's not physically possible.
This is mainly due(besides the small size and limited movement) to the fact that you must have an exciter that is capable of providing a strong vibrational force or push to ''excite'' the panel material.

Any audible peaks that occur can be tuned out with suspension or added dampening(as you have found) with rubber disks etc. as NXT and Podium Sound do in their products. I have not found that this is of any great concern at this stage, but will be visiting this area when the completion stage is near.

Piezos are o.k as DML's when attached to small panels such as notebook computer screens and cell phones - that's it, unfortunately🙁

I would love to see a 10 inch diameter piezo with a few small hard feet that attach to any resonant lightweight panel - now that would be interesting!!!😉
 
#309
jzagaja, yes, but........they do not have the same driving ''force'' as do the piston drivers. This is a physical/mechanical ''push'' with weight behind it - something that only a voice coil and strong magnetic field can do effectively to make a DML produce enough sound level.

For example : hit a bell with a hammer
now hit it with a small stick of balsa wood..................what happens?

You must see a raw exciter, hold it(but only briefly)in your hand with a signal applied and place it against various objects....even on top of your head...LOL!

The thing can really VIBRATE - STRONGLY with great intensity. A Piezo will only buzz in comparison.
 
#312
I just got a pair of Dayton exciters and am starting my experiments. First cardboard (kind of a reference, since everyone has tried it). I just pressed it to the board and, well, sounded very strongly like cardboard. Then I tried a 97x77 cm Rohacell board I have left from my Planot experiments. No bass at all despite of the size (cardboard of the same size has a lot more). But the highs, uh la la. Reminds me more of the BMR than the Podium Sound. I think I could really live with it, and this is just a first test with the exciter mounted with its plastic enclosure.
Balsa plywood is ordered for further testing.
 
#316
el'OL.............. and everyone : sorry..........but I just can't help myself .................................I TOOOOOOOOOOOOOOOLLLLLLLLLDDDDD YOU SOOOOOOOO😀 😉 😀 😉 😀 😉 !!!

Have I missed something?.......what's a ''BMR''??
 
#318
aczern said:


BMR = Balanced Mode Radiator

http://www.nxtsound.com/420.html

http://www.nxtsound.com/index.php?id=428
Click to expand...


To further specify this:
My Rohacell panels have much better transparency (which I define as absence of fog) than the Podium Sound. But same as the BMR (that also consists of Rohacell, with concentric brass rings in the diaphragm) it has somewhat elevated harmonic distortion because of the non-linear behaviour of the material.
Altogether I wonder why no masses of DML panels are hanging on the walls across the world, combined with subs of course, and the MUCH worse "virtually invisible" speakers of this famous four letter company are still much more popular.
 
#319
The prototypes of ma three-ways are running and they definitely needn´t fall in shame. A 6.5" fullrange combined with a conventional silk dome above 5 kHz seems to be a very good compromise between compression and transparency. I can imagine this could also be a physiologically correct crossover point in a dynamic/piezo DML hybrid. What remains is my question why one sees not more flat speakers on walls, but the current implementations don´t fully meet my audiophile demands.
 
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